在上一篇中我们主要了了解micro:bit的的服务特性，今天我们主要用micro:bit的几个特性来读取以及改写
在上篇我们已经将我们所需的UUID写入，接下来只要对代码进行小部分修改以及增添就行
首先我们要添加读写按钮 接着再添加读取型号函数，之后添加改变led的写函数。
读取micro:bit开发板的名称
function readModelNumber()
{
console.log(“readModelNumber”);
if (!connected)
{
alert(“Error: Discover and connect to a device before using this function”);
return
}
if (!services_discovered)
{
alert(“Error: Service discovery has not yet completed”);
return
}
if (!has_device_information_service)
{
alert(“Error: The connected device does not contain the device information service”);
return
}
if (!has_model_name_string)
{
alert(“Error: The connected device does not contain the model name string”);
return;
}
model_number_string.readValue()
.then(value => {
data = new Uint8Array(value.buffer);
model_number_string = new TextDecoder(“utf-8”).decode(data);
console.log(model_number_string);
document.getElementById(“model_number”).innerHTML =
model_number_string;
})
.catch(error => {
console.log(‘Error: ‘ + error);
alert(‘Error: ‘ + error);
return;
});
}
控制LED灯的亮灭
function randomLEDs()
{
console.log(“randomLEDs”);
if (!connected)
{
alert(“Error: Discover and connect to a device before using this function”);
return
}
if (!services_discovered)
{
alert(“Error: Service discovery has not yet completed”);
return
}
if (!has_led_service)
{
alert(“Error: The connected device does not contain the LED service”);
return
}
if (!has_led_matrix_state)
{
alert(“Error: The connected device does not contain the LED matrix state characteristic”);
return;
}
var led_array = [0, 0, 0, 0, 0];
led_array[0] = Math.floor(Math.random() * 32);
led_array[1] = 1;
led_array[2] = 2;
led_array[3] = 3;
led_array[4] = 4;
var led_matrix_data = new Uint8Array(led_array);
led_matrix_state.writeValue(led_matrix_data.buffer)
.then(_ => {
console.log(‘LED matrix state changed’);
})
.catch(error =>{
console.log(‘Error ‘+ error);
alert(‘Error: ‘ + error); return;
});
}
填加控制小灯和读取开发板名称的按钮
Reading and Writing
Write Charateristic - Randomise Lights
Read Charateristic - Model number
效果如下图：
当我们点击Read Model Number执行读取型号函数在下方显示型号
当我们点击Randomise LEDs执行改变led函数，板子上led灯发生改变
